I think the little girl is adorable, but in all honesty I think the best way to choose would be to take Butt with you and see how the puppies interact with him and you. Whichever one seems more active, playful, cuddly, etc. should the best choice, yes? And I mean, with two completely adorable puppies, how else could you choose between them???
Congrats! If it weren't for Bella's recent "strike" for behaving I would be soooooooooo envious! She's keeping me "puppy proofed" at the moment!
By the way, Mutt is a good choice. Beavis is cute too. Definitely let us know which one comes home with you!